Update ICU to 58.1

source/common/ucharstriebuilder.cpp

Index: source/common/ucharstriebuilder.cpp
diff --git a/source/common/ucharstriebuilder.cpp b/source/common/ucharstriebuilder.cpp
index 05255b48c9b3c88323defb5fa0ee45c9ad6ef25b..412a58a45d6bd0f58b4b5b990943bc1ccf2c0a5d 100644
--- a/source/common/ucharstriebuilder.cpp
+++ b/source/common/ucharstriebuilder.cpp
@@ -1,3 +1,5 @@
+// Copyright (C) 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
 /*
 *******************************************************************************
 *   Copyright (C) 2010-2012, International Business Machines
@@ -115,7 +117,7 @@ UCharsTrieBuilder::add(const UnicodeString &s, int32_t value, UErrorCode &errorC
             return *this;
         }
         if(elementsLength>0) {
-            uprv_memcpy(newElements, elements, elementsLength*sizeof(UCharsTrieElement));
+            uprv_memcpy(newElements, elements, (size_t)elementsLength*sizeof(UCharsTrieElement));
         }
         delete[] elements;
         elements=newElements;